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| Titel |
Trends in peroxyacetyl nitrate (PAN) in the upper troposphere and lower stratosphere over southern Asia during the summer monsoon season: regional impacts |
| VerfasserIn |
S. Fadnavis, M. G. Schultz, K. Semeniuk, A. S. Mahajan, L. Pozzoli, S. Sonbawne, S. D. Ghude, M. Kiefer, E. Eckert |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 23 ; Nr. 14, no. 23 (2014-12-04), S.12725-12743 |
| Datensatznummer |
250119205
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| Publikation (Nr.) |
 copernicus.org/acp-14-12725-2014.pdf |
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| Zusammenfassung |
We analyze temporal trends of peroxyacetyl nitrate (PAN) retrievals from the
Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) during
2002–2011 in the altitude range 8–23 km over the Asian summer monsoon
(ASM) region. The greatest enhancements of PAN mixing ratios in the upper
troposphere and lower stratosphere (UTLS) are seen during the summer monsoon
season from June to September. During the monsoon season, the mole fractions
of PAN show statistically significant (at 2σ) positive trends from
0.2 ± 0.05 to 4.6 ± 3.1 ppt yr−1 (except between
12 and 14 km) which is higher than the annual mean trends of 0.1 ± 0.05 to
2.7 ± 0.8 ppt yr−1. These rising concentrations point to
increasing NOx (= NO + NO2) and volatile organic compound
(VOC) emissions from developing nations in Asia, notably India and China.
We analyze the influence of monsoon convection on the distribution of PAN in
UTLS with simulations using the global chemistry–climate model
ECHAM5-HAMMOZ. During the monsoon, transport into the UTLS over the Asian
region primarily occurs from two convective zones, one the South China Sea
and the other over the southern flank of the Himalayas.
India and China host NOx-limited regimes for ozone photochemical
production, and thus we use the model to evaluate the contributions from
enhanced NOx emissions to the changes in PAN, HNO3 and O3
concentrations in the UTLS. From a set of sensitivity experiments with
emission changes in particular regions, it can be concluded that Chinese
emissions have a greater impact on the concentrations of these species than
Indian emissions. According to SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) NO2 retrievals NOx
emissions increases over India have been about half of those over China
between 2002 and 2011. |
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